In recent years, environmental issues have become an increasing concern for government and for citizens. Some pollutants, such as sulfur dioxide, have been a concern for many years. More recently, pollutants that contribute to global warming, such as carbon dioxide, have grown in prominence as well. Since a significant portion of the carbon dioxide generated each year is produced by vehicles powered by gasoline or diesel fuels, there has been an increase in interest in using alternative fuels to reduce these emissions. Alternative fuels include biodiesel, which is produced from plant oils (most commonly soybean oil). Alternative fuels also include ethanol, hydrogen, natural gas, and biobutenol. Electricity can also be considered an alternative fuel when used in an electric car.
Although many consumers want to help against global warming, average consumers may not know what to do to reduce carbon dioxide emissions. Often, they will have trouble determining what practices are most effective. In recent years services have arisen that allow consumers to help offset their impact on the environment. The most well-known are organizations that allow consumers to make themselves “carbon-neutral” by, for example, paying an organization to plant trees sufficient to offset the carbon they produce. Another common mechanism is for an organization to invest the offset money in activities that are environmentally friendly, such as clean power generation. Still, it is hard for consumers to find ways to directly understand the impact of their efforts. Even purchasers of environmentally friendly cars would benefit from knowing how useful their efforts are. Therefore, it would be useful to have a way for consumers to track and take advantage of the benefits they are providing by using environmentally friendly technologies.